Adjustable strut



Dec. 15, 1964 n. CARTER ADJUSTABLE STRUT Filed March 12, 1.962

F I G 4 III F I G 3 r W M 0 w L w 2 a 6 w F United States Patent3,161,395 ADJUSTABLE STRUT Lewis B. Carter, Richardson, Ten, assignor to(latter Craft, ind, Plano, Tex a corporation of Belaware Filed Mar. 12,1962, tier. No. 179,027 Claims. (Cl. 248- 35d) This invention relates toa ratchet system and more particularly to an adjustable supporting strutsystem.

It is oftentimes desirable and sometimes necessary to tilt the top of adesk or table. A desk or table top that is tiltable and is hinged at thefront edge may be supported by one or more struts at the rear edge or onthe sides. In most instances, the strut is adjustable within certainlimits to provide a reasonable range of angles of tilt. There are manytypes, of struts which are purported to be suitable for such purposes.However, they are not entirely satisfactory because they generallyinvolve arms and the like which must be folded or unfolded, or theyemploy screw devices which must be engaged or employed.

In contrast to such systems, the present invention relates to anadjustable strut which operates automatically when actuated in thepreferred manner and includes a positive stop at any of a plurality ofangles. By the present invention a strut is quickly and easilyadjustable and operates'withont manipulation other than to raise the topto the desired position.

disengaged, and in some other types frictional devices are 1Accordingly, it is an object of the present invention to provide animproved adjustable ratchet support strut.

Another object of the invention is to provide a wholly adequate ratchetsupport strut which is operable without manipulation other than movementof its supported member to a desired attitude.

A furtherobject of the invention is to provide a support strut with aminimum number of parts and at a minimum cost.

More particularly, in accordance with the present invention, there isprovided a pair of inner andouter telescoping elongated members movablewith respect to each other between extended and retracted positions. Theoutter memberincludes a pair of opposed arcuate structures abuttingalong one longitudinal edge while the other pair of edges overlie andsupport an elongated ratch. The

ratch includes a pair of inwardly facing notches spaced.

apart a predetermined distance by a plurality of inwardly facing ratchetteeth. A detent is pivotally supported on the inner member resilientlybiased toward the ratch for positive engagement with the ratchet teeth.

In a more specific.aspect of the invention, there is provided anadjustable strut which comprises a tubular structure having alongitudinal, toothed rack with theteeth thereon facing inwardly andhaving an elongated slotextending parmlel to the rack in spacedcircumferential relation. An armor is provided for the structure whichspans the slot and is secured to the structure on opposite sides of theslot. A tubular member telescopes within thestructure and includes apawl pivotallymounted thereon as to engage the teeth on the rack. Aguide element is mount ed on the tubular member for travel in the" slotto main-.

ice

GURE 1;

FIGURE 3 is a sectional view taken along line 33 of FIGURE 1;

FIGURE 4 is a schematic perspective view showing one installation of theinvention;

FIGURE 5 is a fragmentary longitudinal sectional view of anotherembodiment of the invention; and

FIGURE 6 is a sectional view of FIGURE 5 taken along lines 6-6 withcertain parts omitted.

Referring now to FIGURES l, '2 and 3, an adjustable rigid strut device11 comprises an inner cylinder 13 which is formed by two semicylindricalmembers 15 and 17, FIGURES 2 and 3. Members has an integrally formedoutwardly extended plate portion 21. Member 17 has a plate portion 23,which is substantially parallel with plate 21. A bar 25, havingsubstantially rectangular cross section, is disposed between and fixedlyattached to the opposed inner surfaces of the plates 21, 23. Theinwardly directed face 27 of the bar has two rectangularlyshaped notches29 and 31, FIGURE 1, which are spaced apart a predetermined distance. Aplurality of ratchet teeth 33 are formed in the surface 27 of the bar 25between notches 29 and 31.

Telescoped in the cylinder 13 is a tubular member 3-5, FIGURE 1, whichextends from the top end of the cylinder 13. The lower end of the member35 is cut away to provide an integral, downwardly projecting arcuatemember 39 which supports a pair of spaced parallel plates 41 and 43,FIGURE 3. A detent 45 is mounted between the plates 4.1.and 43. Detent45 is free to rotate about a pivot pin 47 supported by the plates 41,43. The pivot pin 4! is located near the lower end of the plates 41, 43.The detent is biased by spring 49 to engage the ratch 33 as member 35 ismoved axially in the first member 13. Coil spring 49 encircles the pivotpin 47 and is so arranged that one end 51 is secured to the detent 45while the other end 53 is secured to the plate 41. Coil spring 49 keepsthe detent 45 in engagement with the teeth 33.

A longitudinal slot 53 is formed in cylinder 13 opposite teeth 33. Theslot 53 thus formed is approximately equal in length to the distancebetween the upper end of notch 31 and the lower end of notch 29.

A bolt 55 is threaded in the arcuate member 32 along its longitudinalaxis. The head 57 of bolt 55 slides in slot 53. Bolt head 57 isconstrained to move longitudinally only within the slot '53. By thismeans member 35 may extend from cylinder 13 only so far as permitted bythe bolt heat 57 working in the slot 53. In like manner, the extent towhich member 35 telescopes into the cylinder 13 is limited by the bolthead 57 abutting the lower extremity of the slot 53.

A slotted cylindrical jacket 59 having an inner diameter correspondingto the outer diameter of the cylinder 13 partially surrounds cylinder13. Jacket 59 couples elements 15 and 17 together, maintaining thelongitudinal edges 19 in abutting relation.

An aperture 61 of diameter slightly greater than the bolt head 57 isprovided near the upper end of the jacket 59. Aperture 61 is inregistration with the bolt head 57 when in its uppermost position. Thepresence of the aper-.

An anchor hole 63 is formed at the bottom of cylinder 13 and jacket 59.A similar anchor hole 65 is formed near the top of the member 35. Holes63, 65 receive pivot pins (not shown) for mounting the strut. Apertures63 and 65 are axially aligned and are in quadrantal relationship to theaperture 61.

FIGURES and 6 illustrate an embodiment of a modi fication of the presentinvention wherein a tube 67 is mechanically worked to form a ratchetstructure 73 in a wall thereof. The ratchet structure is terminated intwo sockets such as socket 79, only one socket being shown. Achannel-shaped structure 75 is provided with a pair of outwardlyextending flanges 87, 89 which overlie and are attached to the outerperiphery of the cylinder 67 An inner tubular structure 91, which issimilar to the structure 35, telescopes the outer tubular member 67. Theinner structure 91 is provided with a detent 93 and a coil spring 95 inengagement therewith. A pair of supporting plates such as plate 97 aremounted on an arcuate extension 101 of the structure 91.

The embodiment shown and described in connection with FIGURE 5 will bequite adequate in many applications. However, where great weight is tobe supported or where inordinate forces are applied as may beencountered in school use and the like, the device of FIGURE 1 will bemore suitable. The reinforcement provided by a double wall structurewhere the jacket 59 is wrapped around and secured to elements 15 and 17permits the device to withstand great abuse. Tendency to deform thecylinder to an oval shape is overcome and a cylindrical slideway for themember 35 is maintained.

To understand the manner in which the invention is used, reference ismade to FIGURE 4. The device 11 is pivotally connected to a basestructure 103 by a pivot pin 105 through the aperture 63. The device 11is pivotally connected, likewise, to the tiltable top 107 by a pin 109through the aperture 65. When the top 107 is hinged at its front hingededge 111, the device 11 may be extended longitudinally. As inner tubularmember 35 is withdrawn, the detent 45 engages the ratchet teeth 33 asshown in FIGURE 1. The top 107 will remain at the selected angle of tiltbecause the upwardly and inwardly directed force developed between thedetent and the ratchet teeth 33 is resolvable into a force counteringthe downward force of the table top and any load which may be imposedthereon. As the table top 107 is further raised upwardly, the detent 45,under urging of the coil spring 59, continues to engage the ratchetteeth 33.

In order to lower the table top 107 to its initial position, which maynot necessarily be horizontal, it is only necessary to raise the rearedge 113 until the second tubular structure 15 is extended so that thedetent 45 rotates upwardly in the upper notch 31 as shown in FIGURE 5.Thereafter, the top may be brought to its initial position without thedetent 45 engaging the ratchet teeth 33. Thereafter, upward movement ofthe rear edge 113 causes the detent 45 to reverse itself in the lowersocket 29 to reengage the ratchet teeth 33 in the manner describedhereinbefore.

It will be clear that the device 11 operates automatically as the top107 is tilted upwardly and that special manipulation of the device isnot necessary.

Thus, it will be seen that, in the embodiments shown and described, theinvention is characterized by a pair of extensible inner and outertelescoping tubular members, the inner one supporting a pivotable detentwhich is urged by resilient bias apparatus into engagement with a ratchstructure supported by the outer member in confronting and abuttingrelation thereto. In a preferred embodiment of the invention, thetelescoping tubular members are of metal such as steel, aluminum and thelike, while the ratch, pawl and resilient bias apparatus are also of thesame metal. Other materials may be found more suitable and effectivelyused without'limitation.

Having described the invention in connection with certain embodimentsthereof, it is understood that further modifications may suggestthemselves to those skilled in the art and it is intended to cover suchmodifications as fall within the scope of the appended claims.

\Vhat is claimed is:

1. An adjustable strut which comprises:

(a) an elongated toothed rack,

(b) a tubular structure having a first longitudinal slot to receive saidrack, and being secured thereto with the rack teeth facing inwardly,said structure having a second longitudinal slot extending parallel'tosaid first slot in spaced circumferential relation,

(0) an outer armor encircling said structure and secured theretoadjacent to the edges of said first slot,

((1) a tubular member telescoping in said structure and including a pawlpivotally mounted thereon to engage said teeth, and

(e) a stop element mounted on said tubular member for travel in saidsecond slot to maintain a predetermined rotational orientation betweensaid pawl and said rack.

2. An adjustable strut which comprises:

(a) an elongated toothed rack,

(b) a pair of semicylinders abutting at one pair of edges and flanged atthe opposite pair of edges to form a tubular structure having a firstlongitudinal slot between the flanged edges in which said rack issecured with the crowns of the teeth thereon facing inwardly, saidstructure having a second elongated slot extending parallel to saidfirst slot in spaced circumferential relation,

(c) a slotted cylinder encompassing said structure in intimate relationand secured thereto along the base of the flanges at said flanged edges,

((1) a tubular member telescoping in said structure and including a pawlpivotally mounted thereon to engage said teeth, and

(e) guide means mounted on said tubular member for travel in said secondslot to maintain a predetermined rotational orientation between saidpawl and said rack.

3. An adjustable strut which comprises:

(a) a tubular structure having a longitudinal toothed rack with thecrowns of the teeth thereon facing inwardly, said structure having anelongated slot extending parallel to said rack at a position spacedcircumferentially therefrom,

(b) an outer armor for said structure spanning said slot,

(0) a tubular member telescoping in said structure and including a pawlpivotally mounted thereon to engage said teeth, and

(d) an element mounted on said tubular member for travel in said slot tomaintain a predetermined rotational orientation between said pawl andsaid rack.

4. An adjustable strut which comprises:

(a) a tubular structure having a longitudinal toothed rack with thecrowns of the teeth thereon facing inwardly and an enlarged indentationat each end of said rack,

- (b) an outer armor encompassing said structure,

(0) a tubular member telescoping in said structure and including a pawlpivotally mounted thereon to engage said teeth and reversible whenpositioned in each said indentation, and

(d) guide means for maintaining a predetermined r0- tational orientationbetween said pawl and said rack.

5. An adjustable strut which comprises:

(a) a tubular structure having a longitudinal toothed rack with thecrowns of the teeth thereon facing inwardly with an enlarged indentationat each end of said rack and an elongated slot extending parallel tosaid rack and spaced circumferentially therefrom,

(b) an outer armor encompassing said structure,

(c) a tubular member telescoping in said structure and including a pawlpivotally mounted thereon to engage said teeth and reversible whenpositioned in each said indentation, and

(d) an element mounted on said tubular member for travel in said slot tomaintain a predetermined rotational orientation between said pawl andsaid rack.

6. An adjustable strut which comprises:

(a) a pair of semicylinders each having an outwardly directed flange atone edge,

(b) an elongated toothed rack secured between the flanges on saidcylinders to form a tubular structure with the teeth on said rack facinginwardly and an elongated slot extending parallel to and diametricallyopposite said rack,

(c) a slotted cylinder encompassing said structure and secured theretoalong the bases of said flanges,

(a') a tubular member telescoping in said structure and including a pawlpivotally mounted thereon to engage said teeth, and

(e) guide means mounted on said tubular member for travel in said slotto maintain said pawl in alignment with said rack.

7. A support strut comprising:

(a) a pair of inner and outerJtelescoping elongated members with saidinner member being capable of longitudinal movement relative to saidouter member between extended and retracted positions, said outer memberincluding a pair of arcuate structures abutting along one longitudinaledge and having spaced other edges,

(b) an elongated ratch supported between said spaced other edges inconfronting relation to said inner member, said ratch including a pairof inwardly facing notches separated by a plurality of inwardly facingratchet teeth,

(0) a detent pivotably supported by said inner member in biased engagingrelation with said ratchet teeth, (d) resilient bias meansformaintaining said detent in engagement with said ratch,

(e) an arcuate elongated member engaging in confronting relation theouter periphery of said outer member and maintaining said longitudinaledges in abutting relation, and

(f) means for limiting the extensibility of said inner member withrespect to said outer member between said extended and retractedpositions.

8. A support strut comprising:

(a) a pair of inner and outer telescoping elongated members with saidinner member being capable of longitudinal movement relative to saidouter member between extended and retracted positions, said outer memberincluding a pair of arcuatestructures abutting along one longitudinaledge and having spaced other edges,

i (b) an elongated ratch supported between said other spaced edges inconfronting relation to said inner member, said ratch including a pairof inwardly facing notches separated by a plurality of inwardly facingratchet teeth,

(0) a detent pivotably supported by said inner member in biased engagingrelation with said ratchet teeth, (d) resilient bias means for pivotingsaid detent in one said notch into disengaging relation to said'ratchetteeth when said members are in extended position,

and pivoting said detent in said other notch into engaging relation withsaid ratchet teeth when said members are in retracted position, and

(e) an arcuate elongated member engaging in confronting relation theouter periphery of said outer member and maintaining said longitudinaledges in abutting relation.

9. A support strut comprising:

(a) an elongated outer tubular member,

(b) a pair of elongated longitudinal slots in said tubular member,

(c) an arcuate structure overlying the outer periphery of said outertubular member in confronting relation thereto and having a pair ofoutwardly projecting and inwardly facing sockets each disposed oppositean end of said slot with said sockets being separated by a plurality ofinwardly facing ratchet teeth,

((1) closure means overlying said other slot,

(e) an elongated inner tubular member telescoping said outer tubularmember and movable relative thereto between extended and retractedpositions,

(f) a detent pivotably supported by said inner member,

(g) resilient biased means engaging said detent so as to engage saidratchet teeth,

(h) resilient biased means engaging said detent so as to pivot saiddetent in one said socket into disengaging relation to said ratchetteeth when said inner tubular member is in extended position and topivot said detent in said other socket into engaging relation to. saidratchet teeth when said inner tubular member is in the retractedposition, and

(1') means for containing said inner member within said outer memberbetween extended and retracted positions.

10. A support strut comprising:

(a) a pair of inner and outer telescoping elongated members with saidinner member being capable of longitudinal movement relative to saidouter member between extended and retracted positions, said outer memberincluding a pair of arcuate structures each abutting the other along onelongitudinal edge and having spaced other parallel edges,

(11) an elongated ratch supported between said other spaced paralleledges in confronting relation to said inner member, said ratch includinga pair of inwardly facing notches displaced by a plurality of inwardlyfacing ratchet teeth,

(c) a detent pivotally supported by an arcuate elongated memberconnected to said inner member,

(0.) means for maintaining said detent in engagement with said ratch,and

(e) an arcuate elongated member engaging in confronting relation theouter periphery of said outer member and maintaining said longitudinaledges in abutting relation.

References Cited in the file of this patent UNITED STATES PATENTS2,377,949 McMenamy June 12, 1945 2,480,382 Pagliuso Aug. 30,1949

2,892,647 ONeil June 30, 1959 FOREIGN PATENTS 10,368 Great Britain July17, 1888

1. AN ADJUSTABLE STRUT WHICH COMPRISES: (A) AN ELONGATED TOOTHED RACK,(B) A TUBULAR STRUCTURE HAVING A FIRST LONGITUDINAL SLOT TO RECEIVE SAIDRACK, AND BEING SECURED THERETO WITH THE RACK TEETH FACING INWARDLY,SAID STRUCTURE HAVING A SECOND LONGITUDINAL SLOT EXTENDING PARALLEL TOSAID FIRST SLOT IN SPACED CIRCUMFERENTIAL RELATION, (C) AN OUTER ARMORENCIRCLING SAID STRUCTURE AND SECURED THERETO ADJACENT TO THE EDGES OFSAID FIRST SLOT, (D) A TUBULAR MEMBER TELESCOPING IN SAID STRUCTURE ANDINCLUDING A PAWL PIVOTALLY MOUNTED THEREON TO ENGAGE SAID TEETH, AND